Spark-plug.



J. A. GILBERT.

SPARK PLUG.

APPLICAHON man MAY 20. 1914.

Patented May 4, 19]

M2 M ATTORNEYS JOHN ALBERT GILBERT, 0F COCOA, FLORIDA.

SPARK-PL UG.

Application filed May 20, 1914.

T 0 all whom it may concern Be it known that I, JoHN A. GILBERT, acitizen of the United States, and a resident of Cocoa in the county ofBrevard and State of Florida, have made certain new and usefulImprovements in Spark-Plugs, of which the following is a specification.

My invention relates to improvements in spark plugs, and it consists inthe combine tions, constructions, and'arrangements herein described andclaimed.

An object of my invention is to provide a plug which is capable ofgiving a multi plicity of sparks, thereby insuring the explosion of gasin the cylinder upon which the spark plug is located. I

A further object of my invention is to provide a spark plug of the typedescribed having a pluralityoi' spark gaps in series, these gaps beingarranged in a substantially circular are around the bottom of the plug.

A further object of my invention is to provide a. spark plug having aninsulating portion bearing movable terminals with for securing theinsulating portion to the body portion of the plug or removing ittherefrom at will.

Other objects and advantages will appear in the following specificationand the novel features of the device will be particularly pointed out inthe appended claim.

My invention is illustrated in the accompanying drawings forming part ofthis application in which- Figure 1 is a vertical section through theplug, and Fig. 2 is a iierspective iew of the bottom of the plug.

In carrying out my invention I provide an exterior metallic casing 1having a shoulder 2 and a threaded portion 3, the latter being designedto enter the threaded opening in the end of the cylinder (not shown).The casing provided with a terminal 4, as shown in the drawings.Arranged to fit in the casing is a central insulating member 5 which isprovided at its bottom with a recess 6. This central portion bears acentral conductor 7, the latter passing through a head 8, whichsurmountsthe insulating member 5, the nut 9 being provided to fit on theother end of the conductor 7. 0n the bottom of the casing is disposed aninsulating block or plate 10 which bears a series of conductors. ()ne ofthese conductors a has branchesa and a" which are bent laterally. Thebranch a is dis- Specification of Letters Patent.

Patented May 4, 1915. Serial 230. $39,750.

posed in close proximity to a conductor 6, being spaced therefrom by adistance which forms a proper spark gap. The end 6 of the conductorv ois similarly disposed with respect to a conductor 0, the end 0 of theconductor 0 being similarly disposed with respect tothe conductor 03 andthe end d of the conductor d being separated from the terminal 4 inorder to provide a spark gap.

The insulating bottom plug or plate 10 is provided with a central boss11 which is arranged to enter in the recess 6 in the bottom of thecentral insulating member 5. A jam nut 12 holds the central insulatingmember 5 securely by forcing the latter in contact with the Walls of thecasing, the gaskets 13 being provided as shown in the drawing.

From the foregoing description of the' various parts of the device theoperation thereof may be readily understood.

In assembling the plug the conducting member 7 will pass through thebottom of the block I U and up through the central part of the memberThe conductor 7 is provided with a head 14 which limits the upwardmovement, a terminal 15 extending downer); ly beyond the head as shownin the drawngs. The terminal 4 of the easing 1 is placed in a slot 10 inthe insulating plate 10 and the central insulating member is then placedover the rod and secured in position by means of the jam nut 12. It willbe seen that the terminal 4 has a double function. It not only serves asa terminal but cooperates with the socket 10 in the member 10, to form acentering member so as to bring the end terminals of the sparkingcircuit in proper position. The nut 9 is designed to bind the terminalof the lead wire (not shown) against the head 8. When the plug isassembled as described the terminal a of the conductor a is disposed ata proper distance from the terminal 15 to produce a spark. It will beseen that there are five spark gaps, these spark gaps being in seriesbetween the terminul 15 and the terminal 4. The increased number ofspark gaps insures the proper explosion of the gaseous mixture. It oftenhappens that a plug willmiss fire from the fact that the gas immediatelysurrounding the spark gap is not mixed in the proper proportions whilethe gas in another position may be of the right proportions to veryreadily explode. This is especially true in engines having projectingparts on the insides of the cylinders which direct the movement of theincoming charge, thereby creating currents which may bring to theordinary spark gap a charge too rich or too lean to properly explode.This is especially true in engines of the two-cycle type. With myinvention the chances of explosion are increased because of themultiplicity of spark gaps and their distribution about the end of theplug. I have found in practice that this device insures explosion Whereplugs of the ordinary type will not, thereby increasing the power of theengine.

I claim A spark plug comprising a casing, a central insulating membersecured to said casing and provided with a conducting rod, an insulatingplate disposed at one end of said casing and having a portion arrangedto enter said central insulating member, and being provided with a slot,a plurality of conductors carried by said plate and spaced apart fromone another to provide spark gaps, said conducting rod being arranged toproject through said insulating plate and having a portion serving acentral terminal, one of the conducting members being spaced apart fromsaid terminal to provide a spark gap, and a terminal carried by saidcasing and arranged to project through the slot in said insulating plateinto close proximity to another of said conductors but spaced from thelatter to provide a spark gap JOHN ALBERT GILBERT.

Witnesses:

L. S. ANDREWS, R. N. ANDREWS.

